int seeSign( const Board &board, Move move, int threshold ) {
ASSERT(!IsNull(move));
#ifdef ATTACK_TRACE
cout << "see ";
MoveImage(move,cout);
cout << endl;
#endif
ColorType my_side = PieceColor(board[StartSquare(move)]);
ColorType side = my_side;
ColorType oside = OppositeColor(side);
Square square = DestSquare(move);
Square attack_square = StartSquare(move);
Piece attacker = board[attack_square];
Piece on_square = (TypeOfMove(move) == EnPassant) ?
MakePiece(Pawn,oside) : board[square];
Bitboard opp_attacks(board.calcAttacks(square,oside));
if (opp_attacks.isClear()) {
// piece is undefended
#ifdef ATTACK_TRACE
cout << "undefended, returning " << (Gain(move) >= threshold) << endl;
#endif
return Gain(move) >= threshold;
}
int score_list[20];
int swap_score = 0;
int gain;
Bitboard attacks[2];
Square last_attack_sq[2] = {InvalidSquare, InvalidSquare};
attacks[side] = board.calcAttacks(square,side);
attacks[oside] = opp_attacks;
int count = 0;
for (;;) {
last_attack_sq[side] = attack_square;
attacker = board[attack_square];
#ifdef ATTACK_TRACE
cout << " " << PieceImage(TypeOfPiece(attacker))
<< " on " <<
FileImage(attack_square) <<
RankImage(attack_square) <<
" takes " << PieceImage(TypeOfPiece(on_square))
<< endl;
#endif
gain = PieceValue(on_square);
if (TypeOfPiece(attacker) == Pawn && Rank(square,side) == 8) {
if (count == 0) {
// initial capture is a promotion (could be under-promotion)
gain += (PieceValues[PromoteTo(move)] - PAWN_VALUE);
on_square = MakePiece(PromoteTo(move),side);
}
else {
// assume Queen promotion
gain += QUEEN_VALUE-PAWN_VALUE;
on_square = MakePiece(Queen,side);
}
}
else {
on_square = attacker;
}
if (side == my_side)
swap_score += gain;
else
swap_score -= gain;
ASSERT(count < 20);
score_list[count++] = swap_score;
// remove piece we used from attacks
attacks[side].clear(attack_square);
// switch sides
side = OppositeColor(side);
if (count % 2 == 0) {
// If it is our turn to move and we are above the threshold
// then we can exit - if we capture it only improves the score.
if (swap_score >= threshold) {
ASSERT(see(board,move) >= threshold);
return 1;
}
// Futility: If capturing the opponent piece for free does
// not bring us up to the threshold, exit. (Do not cut off
// if we have a potential promotion).
if ((Rank(square,side) != 8 ||
!(attacks[side] & board.pawn_bits[side])) &&
swap_score + PieceValue(on_square) < threshold) {
ASSERT(see(board,move) < threshold);
return 0;
}
} else {
// See if opponent already has captured enough that SEE is
// below threshold
if (swap_score < threshold) {
ASSERT(see(board,move) < threshold);
return 0;
}
// Futility: opponent capture cannot get us below threshold
if ((Rank(square,side) != 8 ||
!(attacks[side] & board.pawn_bits[side])) &&
swap_score - PieceValue(on_square) >= threshold) {
ASSERT(see(board,move) >= threshold);
return 1;
}
}
const Square atk = last_attack_sq[side];
if (atk != InvalidSquare &&
TypeOfPiece(board[atk]) != Knight) {
// add in x-ray attacks if any
Square xray = board.getDirectionalAttack(atk,
-Attacks::directions[atk][square],
side);
if (xray != InvalidSquare) {
attacks[side].set(xray);
}
}
if (attacks[side]) {
// get next opponent attacker
attack_square = minAttacker(board,attacks[side],side);
} else {
// no more attackers (including x-rays)
break;
}
}
ASSERT(count >= 1);
// minimax over the score list
for (int i = count-1; i > 0; --i) {
if (i % 2 == 0) {
score_list[i-1] = max(score_list[i],score_list[i-1]);
} else {
score_list[i-1] = min(score_list[i],score_list[i-1]);
}
}
#ifdef ATTACK_TRACE
cout << "returning " << (score_list[0]>=threshold) << endl;
#endif
ASSERT((score_list[0] >= threshold) == (see(board,move) >= threshold));
return score_list[0] >= threshold;
}
int see( const Board &board, Move move ) {
ASSERT(!IsNull(move));
#ifdef ATTACK_TRACE
cout << "see ";
MoveImage(move,cout);
cout << endl;
#endif
ColorType my_side = PieceColor(board[StartSquare(move)]);
ColorType side = my_side;
ColorType oside = OppositeColor(side);
Square square = DestSquare(move);
Square attack_square = StartSquare(move);
Piece attacker = board[attack_square];
Piece on_square = (TypeOfMove(move) == EnPassant) ?
MakePiece(Pawn,oside) : board[square];
Bitboard opp_attacks(board.calcAttacks(square,oside));
if (opp_attacks.isClear()) {
// piece is undefended
#ifdef ATTACK_TRACE
cout << "undefended, returning " << Gain(move) << endl;
#endif
return Gain(move);
}
int score_list[20];
int swap_score = 0;
int gain;
Bitboard attacks[2];
Square last_attack_sq[2] = {InvalidSquare, InvalidSquare};
attacks[side] = board.calcAttacks(square,side);
attacks[oside] = opp_attacks;
int count = 0;
for (;;) {
last_attack_sq[side] = attack_square;
attacker = board[attack_square];
#ifdef ATTACK_TRACE
cout << " " << PieceImage(TypeOfPiece(attacker))
<< " on " <<
FileImage(attack_square) <<
RankImage(attack_square) <<
" takes " << PieceImage(TypeOfPiece(on_square))
<< endl;
#endif
gain = PieceValue(on_square);
if (TypeOfPiece(attacker) == Pawn && Rank(square,side) == 8) {
if (count == 0) {
// initial capture is a promotion (could be under-promotion)
gain += (PieceValues[PromoteTo(move)] - PAWN_VALUE);
on_square = MakePiece(PromoteTo(move),side);
}
else {
// assume Queen promotion
gain += QUEEN_VALUE-PAWN_VALUE;
on_square = MakePiece(Queen,side);
}
}
else {
on_square = attacker;
}
if (side == my_side)
swap_score += gain;
else
swap_score -= gain;
ASSERT(count < 20);
score_list[count++] = swap_score;
// remove piece we used from attacks
attacks[side].clear(attack_square);
// switch sides
side = OppositeColor(side);
const Square atk = last_attack_sq[side];
if (atk != InvalidSquare &&
TypeOfPiece(board[atk]) != Knight) {
// add in x-ray attacks if any
Square xray = board.getDirectionalAttack(atk,
-Attacks::directions[atk][square],
side);
if (xray != InvalidSquare) {
attacks[side].set(xray);
}
}
if (attacks[side]) {
// get next opponent attacker
attack_square = minAttacker(board,attacks[side],side);
} else {
// no more attackers (including x-rays)
break;
}
}
ASSERT(count >= 1);
// minimax over the score list
for (int i = count-1; i > 0; --i) {
if (i % 2 == 0) {
score_list[i-1] = max(score_list[i],score_list[i-1]);
} else {
score_list[i-1] = min(score_list[i],score_list[i-1]);
}
}
#ifdef ATTACK_TRACE
cout << "returning " << score_list[0] << endl;
#endif
return score_list[0];
}
int do_eco(const string &eco_line)
{
ColorType side = White;
Board board;
int movecount = 0;
stringstream s(eco_line);
const string &str = s.str();
string::const_iterator it = str.begin();
// Follow the opening line
string token;
string code;
string name;
int first_token = 1;
while (it != str.end()) {
// skip spaces
while (isspace(*it) && it != str.end()) it++;
if (it == str.end()) break;
// extract text
string text;
int first = 1;
int quoted = 0;
while (it != str.end() && (quoted ? (*it != '"') : !isspace(*it))) {
if (first && *it == '"') {
quoted++;
it++;
first = 0;
continue;
}
text += *it++;
}
if (first_token) {
code = text;
first_token = 0;
continue;
}
else if (quoted) {
name = text;
break;
} else if (text.length() == 0) {
break;
}
// skip numbers
if (isdigit(text[0])) continue;
if (!isalpha(text[0])) return -1;
// parse the move
Move m = Notation::value(board,side,Notation::SAN_IN,text);
if (IsNull(m) ||
!legalMove(board,StartSquare(m),DestSquare(m)))
{
cerr << "Illegal or invalid move: " << text << endl;
return -1;
}
else
{
++movecount;
board.doMove(m);
}
side = OppositeColor(side);
}
if (code.length()) {
cout << '{' << '"' << code << '"' << ", ";
write_64(board.hashCode(),cout);
cout << " ,";
if (name.length())
cout << '"' << name << '"';
else
cout << '"' << '"';
cout << "},";
cout << endl;
}
return 0;
}
